from the <global> section of that keymap.xml: <record>Screenshot</record>. Apparently the graphic included which explains what does what is wrong. You will simply need to map it to something else. It would be ill-advised to map a button to the actual Restart function, instead you should map the Shutdown menu, which is apparently already mapped to DVD Menu.
AFAIK it is IMPOSSIBLE to map or change IGR codes in any way since they are part of your BIOS...